Numerous solid antiperspirant and/or deodorant compositions are described in the chemical and cosmetic literature. These compositions are generally emulsion sticks or suspensoid sticks. Emulsion sticks contain a solution of the antiperspirant and/or deodorant ingredient incorporated into the stick via an emulsion. Although emulsion sticks are desirable in certain respects, they tend to be unstable, exhibit tackiness, and leave a visible residue on the skin after use. Suspensoid sticks contain the powdered antiperspirant and/or deodorant ingredient suspended in the stick without the use of water or an emulsion. While suspensoid sticks have stability, they tend to leave a white, chalky residue on the skin after application.
With respect to deodorant activity, sodium bicarbonate has long been recognized for its deodorant properties, and has commonly been used as a household deodorant. Plain powdered sodium bicarbonate, or sodium bicarbonate diluted with talc or other filler, has been used as an underarm deodorant as disclosed in U.S. Pat. No. 4,382,079. Other publications which describe cosmetic stick compositions containing a bicarbonate deodorant include U.S. Pat. No. 4,822,602, U.S. Pat. No. 4,832,945, and U.S. Pat. No. 4,440,742, all of which are incorporated herein by reference.
However, the development of a practicable and effective composition in cosmetic stick form which has deodorization capacity, and which is capable of consumer acceptability, presents many factors that are unique. Because sodium and potassium bicarbonate have only limited solubility in water, alcohol, and other solvents, the preparation of a composition suitable for dispensing in cosmetic stick form has involved many processing obstacles. In addition to the problem of limited solubility, sodium bicarbonate often is incompatible with other ingredients of conventional stick compositions. Also, the dimensional stability of the cosmetic stick containing sodium bicarbonate, and the esthetic appearance and the "feel" on the skin, are just a few of the additional difficulties encountered in the preparation of a low-residue, deodorant, cosmetic stick product.
A recent trend is toward the development of cosmetic sticks that have light transmitting properties, i.e., the cosmetic sticks are translucent or transparent in light transmitting properties, and engender a perceived appearance of purity.
Cosmetic sticks which are soap-based and which have a content of sodium bicarbonate as a deodorant ingredient typically are opaque in appearance. U.S. Pat. No. 4,440,742 describes anhydrous and water-based deodorant cosmetic sticks which contain sodium bicarbonate, and which vary from opaque to transparent in appearance as determined by the proportions of sodium bicarbonate and water, in combination with other ingredients.
U.S. Pat. No. 5,424,070 describes a transparent solid stick composition containing ingredients such as propylene glycol, water, sodium stearate and Eumulgin L.
There are difficulties associated with the preparation of water-based cosmetic stick products which contain sodium bicarbonate as a deodorant ingredient. Thus, the transparency properties do not have long-term stability. Acceptable degrees of hardness and smoothness are not readily achieved, and an unpleasant cool-wetness is experienced when the cosmetic stick is applied to the skin surface.
As such, there is a continuing interest in the development of water-based deodorant cosmetic stick products which have a high degree of consumer acceptance.
In pursuing this objective, various clarifying substances have been utilized to render an opaque stick translucent or a translucent stick transparent. Unfortunately, these efforts have not been very successful. As can be seen from most of the patents mentioned above, the standard clarifying surfactants have not been able to reliably render sodium bicarbonate containing deodorant stick products transparent. Therefore, there remains a need for a different type of clarifier ingredient for incorporation into alkali metal bicarbonate containing deodorant stick products.
Complexing agents such as polyfunctional polymeric materials have the ability to solubilize a number of substances. One class of substances that has been used in formulations (other than deodorant sticks) which contain sodium bicarbonate are the polyalkylenimines. These materials have been mentioned in formulations in the dental care area, primarily in dentrifice formulations, as complexing agents for a zinc compound. See for example U.S. Pat. No. 4,022,880; U.S. Pat. No. 4,082,841; U.S. Pat. No. 4,522,806, and U.S. Ser. No. 8/269,155, filed Jun. 30, 1994 (now allowed), all of which are incorporated herein by reference. Of special note is the last mentioned allowed U.S. patent application, as that patent also contains sodium bicarbonate and there is no deleterious effects on the sodium bicarbonate by virtue of incorporating the polyamine. It should be especially noted that the purpose of the polyamine compound in all of the foregoing patents is to solubilize a zinc containing compound. There is no teaching or suggestion in any of these patents that the polyamine would have any effect on the light transmittance properties of an alkali metal bicarbonate formulation which, in the absence of both the zinc compound and the polyamine, would otherwise not be transparent.